Numerical Simulation and Diagnosis of a Dense Fog in Beijing and Its Penumbra
北京及其周边地区一次大雾的数值模拟及诊断分析

The fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model was utilized to simulate a dense fog occurred in Beijing and the area around on 1-4 December 2002,the results of simulation in formation and dissipation of the fog are coincide with the real situation,in the same time,the mechanism of formation and maintenance of the fog are analyzed,and the physical process of formation and development is also discussed.Sensitive experiments are performed for understanding the role of radiation.The results showed that longwave radiative cooling is very important for the formation of the fog in addiation to steady atmospheric stratification and plenty of moisture.And the active microphysics process near the ground and stronger radiative cooling on the top of the fog result in the burst development of fog.The fog dissipation was influenced most by shortwave radiation.In addiation,the sustentation of the deep inversion play a decisive role in the course of prolonged fog.